温度应力对既有混凝土连续箱梁桥开裂的影响分析

采用三维空间实体单元，在分析连续箱梁桥温度应力分布规律的基础上，研究了温度梯度、箱梁的肋板与顶板刚度比以及跨径比等参数变化对温度应力的影响，并分析比较了按《公路桥涵设计通用规范》JTJ021-89版和JTG D60-2004版计算的温度应力。结果表明，在JTG D60-2004版温度梯度荷载作用下，箱梁顶板上下缘产生较大的横向拉应力，顶底板上下缘产生较大的纵向拉应力，产生较大温度应力处与实桥出现裂缝的部位基本吻合，从中揭示了温度应力对既有混凝土连续箱梁桥开裂的影响。

Analysis of Temperature Stress for Existing Continuous Concrete Box Girders Cracking

Using 3D solid finite elements, distribution pattern of temperature-induced stresses in continuous concrete box girders am investigated. The thermal gradient actions and the variation of some critical parameters am analyzed, such as the stiffness ratio of the rib to top slab, and the ratio of side-to-middle span, At the same time, the thermal gradient effects am compared according to the design specification of JTJ 021-89 and the updated version of JTG D60-2004. The results of analysis show that there exist high transverse tensile stresses on the top slab and high longitudinal tensile stresses on the top and bottom slab. By comparing the theoretical results at the potential locations of maximum tensile stresses to the practical cracks investigated in the same project, the influnenece of temperature stress am discussed in the existing continuous bridges of concrete box girder.